1. Field of the Invention
The present invention relates to a configurative relationship between a rotary electric machine and an inverter unit for controlling the rotary electric machine in an automotive electric motor-generator apparatus mounted to an electric vehicle or a hybrid vehicle, etc., and relates particularly to a construction for mounting the inverter unit enabling torque characteristics of the rotary electric machine to be improved.
2. Description of the Related Art
In recent years, reductions in CO2 emissions are being sought, backed by a need to prevent global warming. Reduction of CO2 in vehicles means improving fuel consumption performance, and development and testing of electric vehicles (EVs) or hybrid vehicles (HEVs) are being advanced as one solution.
In particular, functions demanded of rotary electric machines mounted to hybrid vehicles include idling when a vehicle is stopped, energy regeneration during deceleration, torque assistance during acceleration, etc., and improvements in fuel consumption performance are becoming possible by implementing these functions.
An electric motor-generator is mounted transversely outside an engine. A belt is placed around the electric motor-generator and a crank shaft pulley such that bidirectional transmission of driving forces can be performed between the electric motor-generator and the engine.
Thus, during electric motor operation, direct-current power from a battery is converted to alternating-current power by an inverter. This alternating-current power is supplied to the electric motor-generator, driving the electric motor-generator to rotate. Torque therefrom is transmitted to the engine by means of the belt, starting the engine. During electric power generation, on the other hand, a portion of the driving force from the engine is transmitted to the electric motor-generator by means of the belt, generating alternating-current power, and this alternating-current power is converted to direct-current power by the inverter and stored in the battery. (See Patent Literature 1, for example.)
Patent Literature 1: Japanese Patent Laid-Open No. 2001-95103 (Gazette: FIG. 2)
In conventional automotive electric motor-generator apparatuses, because the inverter is disposed far away from the electric motor-generator, the wiring length of the alternating-current wiring electrically connecting the inverter and the electric motor-generator is long. As a result, because the wiring resistance in the alternating-current wiring is large, increasing voltage drop in the alternating-current wiring, one problem is that situations may arise such as not being able to supply enough electric power to the electric motor-generator to make it output a desired torque, or it being impossible to increase rotation in the electric motor-generator to a desired rotational speed, etc.
It is also conceivable that the wiring resistance might be reduced by increasing the thickness of the alternating-current wiring in order to suppress the voltage drop in the alternating-current wiring. However, in that case, one problem is that wiring weight and wiring costs increase significantly.